Dilator

ABSTRACT

Provided is a dilator capable of increasing the diameter of a hole formed on the wall of a digestive tract and the like while ensuring distal-end flexibility and maintaining pushability and torquability even when a shaft is longer and curved. A dilator includes a hollow shaft having an outer diameter that is smaller at a distal end than at a proximal end, and a grip portion connected to the proximal end of the shaft. A spirally-arranged protruding portion protruding outwardly is provided on an outer peripheral surface of the shaft. The spirally-arranged protruding portion has gaps between adjacent portions along a longitudinal axis of the shaft.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication No. PCT/JP2018/011674, filed Mar. 23, 2018, which claimspriority to International Application No. PCT/JP2017/012024, filed Mar.24, 2017. The contents of these applications are incorporated herein byreference in their entirety.

BACKGROUND

The present disclosure relates to a dilator.

Conventionally, an auxiliary tool called a sheath introducer is usedwhen a catheter is inserted into a body lumen such as a patient's bloodvessel. A sheath introducer includes a sheath for connecting a patient'sbody lumen to the outside of the body, and a dilator to be inserted intothe sheath for expanding a hole formed on a body surface. For example,Japanese Patent Application Laid-Open Publication No. 2008-11867describes a sheath introducer 200 including a sheath 80 and a dilator 70(see FIG. 1 and others).

The above sheath introducer 200 is used as follows: the patient's skinis first perforated at a predetermined location using an introducerneedle, a guide wire is inserted into a body lumen such as a bloodvessel through the resulting hole, a proximal end of the guide wire isinserted into a distal end of the sheath introducer 200 where thedilator 70 is already inserted into the sheath 80, and the sheathintroducer 200 is then inserted into the body lumen along the guidewire. During this, a distal end of the dilator 70 will expand thediameter of the hole formed on the skin. Subsequently, the dilator 70 iswithdrawn from the sheath introducer 200, and then a catheter isinserted into the sheath introducer 200 and is inserted into a bodylumen such as a blood vessel.

Such a sheath introducer is usually designed to be inserted through thepatient's skin, and is generally short and linear as described inJapanese Patent Application Laid-Open Publication No. 2008-11867.Meanwhile, an alternative procedure is performed as follows: anintroducer needle is pushed out of a distal end of an endoscope insertedthrough the patient's mouth or nose instead of through the patient'sskin to perforate the wall of a digestive tract such as a patient'sstomach at a predetermined location, a guide wire is inserted throughthe resulting hole, a proximal end of the guide wire is inserted into adistal end of a dilator, and the dilator is then inserted into the wallof the digestive tract along the guide wire to increase the diameter ofthe hole formed on the wall of the digestive tract.

A dilator for use in such a procedure is designed to be inserted throughthe patient's mouth or nose, and thus needs to be relatively long andgenerally configured so as to be used in a curved state, consideringthat it is to be passed through the digestive tract.

However, an increased length of a dilator may have a problem in that arotational force (torque) and pushing force (pushability) from theuser's hand cannot be transmitted to a distal end of the dilator, whichin turn may preclude increasing the diameter of a hole formed on thewall of a digestive tract. In particular, a curved dilator further had aproblem in that the deterioration of these properties becomes moresignificant.

SUMMARY

The disclosed embodiments have been devised in view of thesecircumstances. An object of the disclosed embodiments is to provide adilator capable of easily increasing the diameter of a hole formed onthe wall of a digestive tract and the like and also capable ofmaintaining pushability and torquability even when a shaft is longer andcurved.

In order to achieve the above object, provided is a dilator including: ahollow shaft having an outer diameter that is smaller at a distal end ofthe shaft than at a proximal end of the shaft; and a grip portionconnected to the proximal end of the shaft, a spirally-arrangedprotruding portion protruding outwardly being provided on an outerperipheral surface of the shaft, and the spirally-arranged protrudingportion having gaps between adjacent protruding portions along alongitudinal axis of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 show an overall view of a dilator according to the disclosedembodiments;

FIG. 2 shows a distal end portion with a view of an inner cavity of thedilator (a multilayer body) shown in FIG. 1;

FIG. 3 shows a cross-sectional view taken along line III-III in FIG. 1;

FIG. 4 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 5 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 6 shows a distal end portion with a view of an inner cavity of thedilator (a multilayer body) shown in FIG. 5;

FIG. 7 shows a cross-sectional view taken along line VII-VII in FIG. 5;

FIG. 8 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 9 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 10 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 11 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 12 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments;

FIG. 13 show an overall view of a dilator according to the disclosedembodiments;

FIG. 14 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments;

FIG. 15 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments;

FIG. 16 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments;

FIG. 17 shows a distal end portion of a dilator according to thedisclosed embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

Below, the embodiments of the present disclosure will be described withreference to the figures. It is noted that the dimensions of thedilators shown in the figures are merely provided to facilitateunderstanding of the embodiments, and do not necessarily correspond tothe actual dimensions.

FIG. 1 shows an overall view of a dilator according to the disclosedembodiments, FIG. 2 shows a front end portion (distal end portion) witha view of an inner cavity of the dilator (a multilayer body), and FIG. 3shows a cross-sectional view taken along line III-Ill in FIG. 1.

In FIGS. 1 and 2, the left side in the figure corresponds to the frontend side (the distal side) which is to be inserted into the body, andthe right side corresponds to the base end side (the hand side, theproximal side) which is to be operated by an operator such as a surgeon.

In FIG. 1, a dilator 1 includes: a multilayer body 7 including a hollowcoil body 3 including a plurality of element wires 3 a, 3 b, 3 c, 3 d, 3e, 3 f, 3 g, 3 h, 3 j, and 3 k (e.g., metal wires) wound around into ahollow shape, and a coil body 5 including a single element wire 5 a(e.g., a metal wire) wound around a surface of the hollow coil body 3 ina direction (clockwise, facing to the distal end) opposite to the hollowcoil body 3 (counterclockwise, facing to the distal end); and aconnector 9 having a hollow shape connected to a proximal end of themultilayer body 7.

Here, the multilayer body 7 has a cylindrical hollow shape at a proximalend portion P3, has a tapered hollow shape at an intermediate portionP2, and has a cylindrical hollow shape at a distal end portion P1.

It is noted that the wires 3 a, 3 b, 3 c, 3 d, 3 e, 3 f, 3 g, 3 h, 3 j,and 3 k correspond to the “first wires,” and the hollow coil body 3corresponds to the “first layer body,” the “shaft,” and the “firstcoil.”

In addition, the wire 5 a corresponds to the “second wire,” and the coilbody 5 corresponds to the “second layer body,” the “spirally-arrangedprotruding portion,” and the “second coil.”

Further, the intermediate portion P2 of the hollow coil body 3corresponds to the “tapered hollow portion” and the “portion having anincreasing outer diameter (tapered shape).” Further, the connector 9corresponds to the “grip portion.”

The hollow coil body 3 is configured such that the wires 3 a, 3 b, 3 c,3 d, 3 e, 3 f, 3 g, 3 h, 3 j, and 3 k are 10 wires (e.g., stainlesssteel wires) wound around into a hollow shape as shown in FIG. 3. Thehollow coil body 3 has a cylindrical hollow shape at the proximal endportion P3, has a tapered hollow shape at the intermediate portion P2,has a cylindrical hollow shape at the distal end portion P1, and has anouter diameter increasing toward a proximal end (an increasing outerdiameter). That is, the hollow coil body 3 has a hollow shape having anouter diameter that is smaller at the distal end than at the proximalend.

In FIG. 2, the dotted lines represent the common inscribed lines of thehollow coil body 3. An inner cavity 8 is formed in the inner side of thecommon inscribed lines of the hollow coil body 3 (see FIG. 3).

It is noted that, while wires made of stainless steel can be used as thewires of the hollow coil body 3, they are not limited to stainless steelwires. They may be wires made of a superelastic alloy such asnickel-titanium. Further, they are not limited to metal wires and may beresin wires.

The coil body 5 is configured such that a wire 5 a (e.g., a stainlesssteel wire) is wound around in a direction (clockwise, facing to thedistal end) opposite to the hollow coil body 3 (counterclockwise, facingto the distal end). Here, the wire 5 a is wound around closely (with asmall winding pitch, for example where adjacent windings of the wire 5 aare in contact with each other) at the proximal end side and is woundaround with gaps between adjacent windings at the intermediate portionP2 and the distal end portion P1. The coil body 5 provides aspirally-arranged protruding portion protruding outwardly (the outermostsurface of the dilator 1, the outermost portion) on an outer peripheralsurface 3L of the hollow coil body 3. The spirally-arranged protrudingportion extends in a spiral shape along its length, and has gaps betweenadjacent portions (adjacent windings of the wire 5 a) along alongitudinal A of the hollow coil body 3. Further, the coil body 5 isprovided at the intermediate portion P2, which corresponds to a portionhaving an increasing outer diameter of the hollow coil body 3.

Further, the amount of gap (space) between adjacent windings of the wire5 a (i.e., the distance between adjacent windings in the longitudinaldirection) is gradually decreased at the proximal end portion P3 towardthe proximal end side thereof. This configuration enables the stiffnessof the dilator 1 (the multilayer body 7) to be gradually changed alongan axis direction (a direction of the longitudinal axis) so that thedilator 1 (multilayer body 7) can easily enter into the inside of anapproach pathway even when the approach pathway meanders.

It is noted that the wire 5 a is configured such that the amount of gapbetween adjacent windings of the wire 5 a is gradually decreased at theproximal end portion P3 toward the proximal end side thereof, but theconfiguration shall not be limited to this. Even when the amount of gapbetween adjacent windings of the wire 5 a is constant from the distalend portion P1 toward the proximal end portion P3, the distal-endflexibility of the dilator 1 (multilayer body 7) can be ensured, and thepushability and torquability of the dilator 1 (multilayer body 7) can bemaintained in a case where the dilator 1 (multilayer body 7) is longerand curved. Further, the screw effect of the single wire 5 a enables thedilator 1 to be advanced not only by a pushing operation but also by arotational operation. Further, the diameter of a pre-formed hole caneasily be increased by the coil body 5 provided at a portion where thehollow coil body 3 has an increasing outer diameter, i.e., at theintermediate portion P2.

Further, with regard to the wire 5 a, the amount of gap between adjacentwindings of the wire 5 a is gradually decreased at the proximal endportion P3 toward the proximal end side thereof. This configuration canhave the following effect: the stiffness of the dilator 1 (themultilayer body 7) in the axis direction can be gradually changed sothat the dilator 1 (multilayer body 7) can easily enter into the insideof an approach pathway even when the approach pathway meanders.

Further, a shaft composed of the hollow coil body 3 (the first coil)including a plurality of wires wound around into a hollow shape canimprove the flexibility of the shaft and the transmissibility of torquevia the shaft. Further, a spirally-arranged protruding portion composedof the coil body 5 (the second coil) including the single wire 5 a woundaround on the outer peripheral surface 3L of the hollow coil body 3 caneasily be formed, can ensure the flexibility of the distal end of thedilator 1, and can improve the torquability by virtue of the elasticityof the second coil. Further, each wire of the hollow coil body 3 iswound around in a direction opposite to the wire 5 a of the coil body 5.Therefore, even when the dilator 1 is rotated in a direction to open thehollow coil body 3, a force is applied in a direction to close the coilbody 5 to prevent the opening of the hollow coil body 3. This allows aforce applied to the connector 9 of the dilator 1 to be transmitted tothe distal end side.

It is noted that the wire 5 a can be made of stainless steel, but thematerial shall not be limited to stainless steel. A metal wire made of asuperelastic alloy such as nickel-titanium may be used. Further, itshall not be limited to a metal wire, and a resin wire may be used.

The length of the dilator is, for example, 2000 mm, preferably 1600 mmto 2500 mm; the length of the distal end portion P1 is, for example, 10mm, preferably 0 mm to 100 mm; and the length of the intermediateportion P2 is, for example, 30 mm, preferably 5 mm to 100 mm. The innerdiameter of the hollow coil body 3 at the distal end is, for example,0.7 mm, preferably 0.4 mm to 1.0 mm, and the inner diameter of thehollow coil body 3 at the proximal end is, for example, 1.5 mm,preferably 1.0 mm to 3.0 mm. The outer diameter of the coil body 5 atthe distal end is, for example, 1.84 mm, preferably 0.8 mm to 3.0 mm,and the outer diameter of the coil body 5 at the proximal end is, forexample, 2.64 mm, preferably 1.4 mm to 5.0 mm. Further, the diameters ofthe wires 3 a to 3 h and 3 j to 3 k are, for example, 0.21 mm,preferably 0.1 mm to 0.5 mm, and the diameter of the wire 5 a is, forexample, 0.36 mm, preferably 0.1 mm to 0.5 mm.

The distal end of the connector 9 is connected to the proximal end ofthe hollow coil body 3 and the proximal end of the coil body 5. Theconnector 9 is made of a resin and has a hollow shape which has an innercavity communicating with the inner cavity 8 of the hollow coil body 3.

Next, an example of an operating mode of the above dilator will bedescribed.

First, a target object is punctured using an introducer needle. Afterthe puncture, a guide wire is inserted through an inner cavity of theintroducer needle, and the introducer needle is withdrawn thereafter.Then, the distal end of the dilator 1 is inserted from the proximal endof the guide wire into the punctured portion. Subsequently, the diameterof a hole at the punctured portion can be increased by pushing androtating the dilator 1 inward.

FIG. 4 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments. In FIG. 4, the left side in thefigure corresponds to the front end side (the distal side) which is tobe inserted into the body, and the right side corresponds to the baseend side (the hand side, the proximal side) which is to be operated byan operator such as a surgeon.

It is noted that the dilator in FIG. 4 basically has the same structureas the dilator 1 in FIGS. 1-3. Therefore, the same number is given tothe same member, and a detailed description will be omitted.

In FIG. 4, a dilator 10 includes: a multilayer body 17 including thehollow coil body 3 including the plurality of wires 3 a, 3 b, 3 c, 3 d,3 e, 3 f, 3 g, 3 h, 3 j, and 3 k wound around into a hollow shape, thecoil body 5 including the single wire 5 a wound around the surface ofthe hollow coil body 3 in a direction (clockwise, facing to the distalend) opposite to the hollow coil body 3 (counterclockwise, facing to thedistal end); and a connector 9 having a hollow shape and being connectedto the proximal end of the multilayer body 17. However, the dilator 10differs from the dilator 1 in that the multilayer body 17 of the dilator10 has a distal-end portion 6 at the distal end of the hollow coil body3 while the multilayer body 7 of the dilator 1 does not. The hollow coilbody 3 having the distal-end portion 6 provided at the distal endcorresponds to the “shaft.”

The distal-end portion 6 is formed by casting a solder material (asilver-tin solder material, a gold-tin solder material, or the like)into the distal end of the hollow coil body 3 and has a substantiallycylindrical hollow shape. Further, the surface of the distal-end portion6 is flat (smooth) while the surface of the distal end of the multilayerbody 7 is uneven.

The dilator 10 having the aforementioned configuration in which thedistal-end portion 6 having a flat surface is connected to the distalend of the multilayer body 17 can further improve insertability into apunctured portion by first pressing the dilator against the puncturedportion, and then pushing and rotating the dilator thereinto.

FIG. 5 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments, FIG. 6 shows the distal endportion with a view of an inner cavity of the dilator, and FIG. 7 showsa cross-sectional view taken along line VII-VII in FIG. 5.

In FIGS. 5 and 6, the left side in the figure corresponds to the frontend side (the distal side) which is to be inserted into the body, andthe right side corresponds to the base end side (the hand side, theproximal side) which is to be operated by an operator such as a surgeon.

In FIG. 5, a dilator 20 includes: a multilayer body 27 including ahollow coil body 21 including a plurality of wires 21 a, 21 b, 21 c, 21d, 21 e, 21 f, 21 g, 21 h, 21 j, and 21 k wound around into a hollowshape; a coil body 22 proximally spaced from a distal end of the hollowcoil body 21 and including a plurality of wires 22 a, 22 b, 22 c, 22 d,22 e, 22 f, 22 g, 22 h, 22 j, 22 k, 22 m, 22 n, 22 p, 22 q, 22 r, and 22s wound around on an outer periphery of the hollow coil body 21 in thesame direction (counterclockwise, facing to the distal end) as thehollow coil body 21; a coil body 23 proximally spaced from a distal endof the coil body 22 and including a plurality of wires 23 a (only one ofthe wires 23 a is indicated by a reference number in FIGS. 5 and 6)wound around on an outer periphery of the coil body 22 in a direction(clockwise, facing to the distal end) opposite to the coil body 22(counterclockwise, facing to the distal end); a coil body 25 including asingle wire 25 a wound around with gaps between adjacent windings on theouter periphery of the coil body 22 in a region distal to a distal endof the coil body 23; and a coil body 24 including a single wire 24 awound around (in the same direction as the wire 25 a) with gaps betweenadjacent windings on the outer periphery of the coil body 21 in a regiondistal to a distal end of the coil body 22. The dilator 20 furtherincludes a connector 9 (not shown) having a hollow shape and connectedto a proximal end of the multilayer body 27.

Here, the multilayer body 27 has a cylindrical hollow shape at theproximal end side of the proximal end portion P3 as in the multilayerbody 7 and the multilayer body 17. However, the multilayer body 27 has astepped and cylindrical hollow shape in the vicinity of the distal endand intermediate portions while the multilayer body 7 and the multilayerbody 17 have intermediate portions with tapered shapes.

It is noted that the wires 21 a, 21 b, 21 c, 21 d, 21 e, 21 f, 21 g, 21h, 21 j, and 21 k correspond to the “third wires,” and the hollow coilbody 21 corresponds to the “third layer body.”

Further, the wires 22 a. 22 b, 22 c, 22 d, 22 e, 22 f, 22 g, 22 h, 22 j,22 k, 22 m, 22 n, 22 p, 22 q, 22 r, and 22 s corresponds to the “fourthwires,” and the coil body 22 corresponds to the “fourth layer body” andthe “portion having an increasing outer diameter.”

Further, the wire 24 a corresponds to the “fifth wire,” and the coilbody 24 corresponds to the “fifth layer body.”

Further, the wires 23 a correspond to the “sixth wires,” and the coilbody 23 corresponds to the “sixth layer body.”

Further, the wire 25 a corresponds to the “seventh wire,” and the hollowcoil body 25 corresponds to the “seventh layer body.”

The hollow coil body 21 and the coil body 22 together correspond to the“shaft” and the “first coil.” The coil body 24 and the coil body 25together correspond to the “spirally-arranged protruding portion” andthe “second coil.”

The hollow coil body 21 is configured such that the wires 21 a, 21 b, 21c, 21 d, 21 e, 21 f, 21 g, 21 h, 21 j, and 21 k are 10 wires (e.g.,stainless steel wires) that are twisted into a hollow shape as shown inFIG. 7. The hollow coil body 21 has a cylindrical hollow shape from thedistal end to the connector 9.

In FIG. 6, the dotted line (the innermost among the three dotted lines)represents the common inscribed line of the hollow coil body 21. Aninner cavity 28 is formed in the inner side of the common inscribed lineof the hollow coil body 21 (see FIG. 7).

Further, the coil body 22 is formed such that the wires 22 a, 22 b, 22c, 22 d, 22 e, 22 f, 22 g, 22 h, 22 j, 22 k, 22 m, 22 n, 22 p, 22 q, 22r, and 22 s are 16 wires (e.g., stainless steel wires) that are twistedon a surface of the coil body 21 as shown in FIG. 7. The coil body 22also has a cylindrical hollow shape from the distal end to the connector9.

In FIG. 6, the dotted line (the intermediate among the three dottedlines) represents the common inscribed line of the coil body 22.

Further, the coil body 23 is formed such that the wires 23 a are 23wires (e.g., stainless steel wires) that are twisted on a surface of thecoil body 22. The coil body 23 also has a cylindrical hollow shape fromthe distal end to the connector 9.

In FIG. 6, the dotted line (the outermost among the three dotted lines)represents the common inscribed line of the hollow coil body 23. Thecoil body 22 is twistedly formed on the surface of the hollow coil body21. This means that the shaft formed from the hollow coil body 21 andthe coil body 22 has a hollow shape and an outer diameter that issmaller at a distal end than at a proximal end.

Further, the coil body 24 is formed such that the wire 24 a (e.g., astainless steel wire) is wound on the surface of the coil body 21, andthe coil body 25 is formed such that the wire 25 a (e.g., a stainlesssteel wire) is wound on the surface of the coil body 22.

Each element wire in the hollow coil body 21, the coil body 22, and thecoil body 23 is wound around closely, and in the coil body 24 and thecoil body 25, a wire is wound around with gaps between adjacent windings(see FIG. 6). The coil body 24 provides a spirally-arranged protrudingportion protruding outwardly (the outermost surface of the dilator 20,the outermost portion) on an outer peripheral surface 21L of the hollowcoil body 21, and the coil body 25 provides a spirally-arrangedprotruding portion protruding outwardly (the outermost surface of thedilator 20, the outermost portion) on an outer peripheral surface 22T ofthe coil body 22. The spirally-arranged protruding portion has gapsbetween adjacent portions (adjacent portions of the wire) along an axisA of the hollow coil body 21. Further, the coil body 25 is provided onthe coil body 22 as a portion in which the shaft has an increasing outerdiameter.

It is noted that metal wires made of stainless steel can be used for thewires of the hollow coil body 21, the coil body 22, the coil body 23,the coil body 24, and the coil body 25, but they are not limited tostainless steel wires. They may be made of a superelastic alloy such asnickel-titanium. Further, they are not limited to metal wires and may beresin wires.

The dilator 20 (the multilayer body 27) can ensure the distal-endflexibility of the dilator 20 (the multilayer body 27) and can maintainthe pushability and torquability of the dilator 20 (the multilayer body27) even when the dilator 20 (the multilayer body 27) is longer andcurved. Further, the screw effect of the single wire 24 a and the singlewire 25 a enables the dilator 20 to be advanced not only by a pushingoperation but also by a rotational operation. Further, the diameter of apre-formed hole can easily be increased by the coil body 25 provided atthe coil body 22 which corresponds to a portion where the shaft has anincreasing outer diameter.

It is noted that when the amounts of gap between adjacent windings ofthe wire 25 a and the wire 24 a are configured so as to be graduallyreduced toward the proximal end side, the following effect can beobserved: the stiffness of the dilator 20 (the multilayer body 27) alongthe axis direction can be gradually changed so that the dilator 20 (themultilayer body 27) can easily enter into the inside of an approachpathway even when the approach pathway meanders.

Further, the shaft (the first coil) composed of the hollow coil body 21and the coil body 22 each including a plurality of wires wound aroundinto a hollow shape can improve the flexibility of the shaft and thetransmissibility of torque via the shaft. Further, the spirally-arrangedprotruding portion (the second coil) composed of the coil body 24including a single wire wound around on the outer peripheral surface 21Lof the hollow coil body 21 and the coil body 25 wound around on theouter peripheral surface 22T of the coil body 22 can be easily formed,can ensure the flexibility of the distal end of the dilator 20 by virtueof the elasticity of the second coil, and can improve the torquability.Further, the wires of the hollow coil body 21 and the coil body 22 arewound in a direction opposite to the wires of the coil body 24 and thecoil body 25. Therefore, even when the dilator 20 is rotated in adirection to open the hollow coil body 21 and the coil body 22, a forceis applied in a direction to close the coil body 24 and the coil body 25to prevent the opening of the hollow coil body 21 and the coil body 22.This allows a force applied to the connector 9 of the dilator 20 to betransmitted to the distal end side.

FIG. 8 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments. In FIG. 8, the left side in thefigure corresponds to the front end side (the distal side) which is tobe inserted into the body, and the right side corresponds to the baseend side (the hand side, the proximal side) which is to be operated byan operator such as a surgeon.

In FIG. 8, a dilator 30 includes: a multilayer body 37 including ahollow coil body 31 including a plurality of wires 31 a, 31 b, 31 c, 31d, 31 e, 31 f, 31 g, 31 h, 31 j, and 31 k wound around into a hollowshape; a coil body 32 including a single wire 32 a wound around on anouter periphery of the hollow coil body 31 from a distal end of thehollow coil body 31 in a direction (clockwise, facing to the distal end)opposite to the hollow coil body 31; a coil body 33 proximally spacedfrom a distal end of the coil body 32 and including a plurality of wires33 a (only one of the wires 33 a is indicated by the reference number inFIG. 8) wound around on an outer periphery of the coil body 32 in adirection (counterclockwise, facing to the distal end) opposite to thecoil body 32 (clockwise, facing to the distal end); and a coil body 35including a single wire 35 a wound around with gaps between adjacentwindings on the outer periphery of the coil body 32 in a region distalto a distal end of the coil body 33 in the same direction (clockwise,facing to the distal end) as the coil body 32 (clockwise, facing to thedistal end). The dilator 30 further includes a connector 9 (not shown)having a hollow shape and being connected to a proximal end of themultilayer body 37.

Here, the multilayer body 37 has a stepped and cylindrical hollow shapeas in the multilayer body 27, but it differs from the multilayer body 27in that the coil body 32 in the multilayer body 37 is formed integrallyand continuously while the coil body 22 and the coil body 24 in themultilayer body 27 are formed as separate members. That is, in the coilbody 32, the wire 32 a is wound around closely at the proximal end sidewhile wound around with gaps between adjacent windings at the distal endside as shown in FIG. 8.

It is noted that the hollow coil body 31 and a portion of the coil body32 where the wire 32 a is wound around closely together correspond tothe “shaft” and the “first coil.” The coil body 35 and the portion ofthe coil body 32 where the wire 32 a is wound around with gaps betweenadjacent windings together correspond to the “spirally-arrangedprotruding portion” and the “second coil.” Further, the portion of thecoil body 32 where the wire 32 a is wound around closely corresponds tothe “portion having an increasing outer diameter.”

The hollow coil body 31 is formed such that the wires 31 a, 31 b, 31 c,31 d, 31 e, 31 f, 31 g, 31 h, 31 j, and 31 k are 10 wires (e.g.,stainless steel wires) that are twisted into a hollow shape as in thehollow coil body 21. The hollow coil body 31 has a cylindrical hollowshape from the distal end to the connector 9.

Further, the coil body 32 is formed such that the wire 32 a (e.g., astainless steel wire) is wound around a surface of the coil body 31. Thecoil body 32 also has a cylindrical hollow shape from the distal end tothe connector 9.

Further, the coil body 33 is formed such that the wires 33 a are 23wires (e.g., stainless steel wires) that are twisted on a surface of thecoil body 32. The hollow coil body 33 also has a cylindrical hollowshape from the distal end to the connector 9. A closely wound portion ofthe coil body 32 is twistedly formed on the surface of the hollow coilbody 31. This means that the shaft formed from the hollow coil body 31and the closely wound portion of the coil body 32 has a hollow shapehaving an outer diameter that is smaller at a distal end than at aproximal end.

Further, the coil body 35 is formed such that the wire 35 a (e.g., astainless steel wire) is formed on the surface of the coil body 32.

Each wire in the hollow coil body 31 and the coil body 33 is woundaround closely (see FIG. 8). The portion of the coil body 32 where thewire is wound around with gaps between adjacent windings provides aspirally-arranged protruding portion protruding outwardly (the outermostsurface of the dilator 30, the outermost portion) on an outer peripheralsurface 31L of the hollow coil body 31, and the coil body 35 provides aspirally-arranged protruding portion protruding outwardly (the outermostsurface of the dilator 30, the outermost portion) on an outer peripheralsurface 32B of the closely wound portion of the coil body 32. Thesespirally-arranged protruding portions each have gaps between adjacentportions (adjacent windings of the wire) along an axis A of the hollowcoil body 31. Further, the coil body 35 is provided at the closely woundportion of the coil body 32, which corresponds to a portion where theshaft has an increasing outer diameter.

It is noted that metal wires made of stainless steel can be used for thewires of the hollow coil body 31, the coil body 32, the coil body 33,and the coil body 35, but they are not limited to stainless steel wires.They may be those made of a superelastic alloy such as nickel-titanium.Further, they are not limited to metal wires and may be resin wires.

The dilator 30 (the multilayer body 37) can ensure the distal-endflexibility of the dilator 30 (the multilayer body 37) and can maintainthe pushability and torquability of the dilator 30 (the multilayer body37) even when the dilator 30 (the multilayer body 37) is longer andcurved. Further, the screw effect of the single wire 32 a and the singlewire 35 a extending contiguously toward the distal end from the proximalend of the coil body 32 can further be improved when the multilayer body37 is rotated. This enables the dilator 30 to be easily advanced notonly by a pushing operation but also by a rotational operation. Inaddition, the coil body 35 is provided in the closely wound portion ofthe coil body 32, which corresponds to a portion where the shaft has anincreasing outer diameter. Therefore, the diameter of a pre-formed holecan be increased more easily.

It is noted that when the amounts of gap between adjacent windings ofthe wire 32 a and the wire 35 a are configured so as to be graduallyreduced toward the proximal end side, the following effect can beobserved: the stiffness of the dilator 30 (the multilayer body 37) alongthe axis direction can be gradually changed so that the dilator 30 (themultilayer body 37) can easily enter into the inside of an approachpathway even when the approach pathway meanders.

Further, a shaft (the first coil) composed of the hollow coil body 31including a plurality of wires wound around into a hollow shape, and thecoil body 32 can improve the flexibility of the shaft and thetransmissibility of torque via the shaft. Further, a spirally-arrangedprotruding portion (the second coil) composed of the coil body 32including a single wire wound around the outer peripheral surface 31L ofthe hollow coil body 31 and the coil body 35 wound around the outerperipheral surface 32B of the coil body 32 can be easily formed, canensure the flexibility of the distal end of the dilator 30 by virtue ofthe elasticity of the second coil, and can improve the torquability.Further, the wires of the hollow coil body 31 are wound in a directionopposite to the wires of the coil body 32 and the coil body 35.Therefore, even when the dilator 30 is rotated in a direction to openthe hollow coil body 31, a force is applied in a direction to close thecoil body 32 and the coil body 35 to prevent the opening of the hollowcoil body 31. This allows a force applied to the connector 9 of thedilator 30 to be transmitted to the distal end side.

FIG. 9 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments.

In FIG. 9, the left side in the figure corresponds to the front end side(the distal side) which is to be inserted into the body, and the rightside corresponds to the base end side (the hand side, the proximal side)which is to be operated by an operator such as a surgeon.

In FIG. 9, a dilator 40 includes: a multilayer body 47 including ahollow coil body 41 including a plurality of wires 41 a, 41 b, 41 c, 41d, 41 e, 41 f, 41 g, 41 h, 41 j, and 41 k wound around into a hollowshape; a coil body 42 proximally spaced from a distal end of the hollowcoil body 41 and including a plurality of wires 42 a, 42 b, 42 c, 42 d,42 e, 42 f, 42 g, 42 h, 42 j, 42 k, 42 m, 42 n, 42 p, 42 q, 42 r, and 42s wound around on an outer periphery of the hollow coil body 41 in thesame direction (counterclockwise, facing to the distal end) as thehollow coil body 21 (counterclockwise, facing to the distal end); a coilbody 43 including a single wire 43 a wound around on an outer peripheryof the coil body 42 from a distal end of the coil body 42 in a direction(clockwise, facing to the distal end) opposite to the coil body 42; anda coil body 44 including a single wire 44 a wound around with gapsbetween adjacent windings on the outer periphery of the coil body 41 ina region distal to a distal end of the coil body 42 in the samedirection (clockwise, facing to the distal end) as the coil body 43(clockwise, facing to the distal end). The dilator 40 further includes aconnector 9 (not shown) having a hollow shape and connected to aproximal end of the multilayer body 47.

Here, the multilayer body 47 has a stepped and cylindrical hollow shapeas in the multilayer body 27, but it differs from the multilayer body 27in that the coil body 43 in the multilayer body 47 is formed integrallyand continuously while the coil body 25 and the coil body 23 in themultilayer body 27 are formed as separate members. That is, in the coilbody 43, the wire 43 a is wound around closely at the proximal end sidewhile wound around with gaps between adjacent windings at the distal endside as shown in FIG. 9.

It is noted that the hollow coil body 41 and the coil body 42 togethercorrespond to the “shaft” and the “first coil.” A portion of the coilbody 43 wound around closely and the coil body 44 together correspond tothe “spirally-arranged protruding portion” and the “second coil.”Further, the coil body 42 corresponds to the “portion having anincreasing outer diameter.”

The hollow coil body 41 is formed such that the wires 41 a, 41 b, 41 c,41 d, 41 e, 41 f, 41 g, 41 h, 41 j, and 41 k are 10 wires (e.g.,stainless steel wires) that are twisted into a hollow shape as in thehollow coil body 21. The hollow coil body 41 has a cylindrical hollowshape from the distal end to the connector 9.

Further, the coil body 42 is formed such that the wires 42 a, 42 b, 42c, 42 d, 42 e, 42 f, 42 g, 42 h, 42 j, 42 k, 42 m, 42 n, 42 p, 42 q, 42r, and 42 s are 16 wires (e.g., stainless steel wires) that are woundaround on a surface of the coil body 41 in the same direction(counterclockwise, facing to the distal end) as the hollow coil body 41.The coil body 42 also has a cylindrical hollow shape from the distal endto the connector 9.

Further, the coil body 43 is formed such that the wire 43 a (e.g., astainless steel wire) is wound around on a surface of the coil body 42.The hollow coil body 43 also has a cylindrical hollow shape from thedistal end to the connector 9.

Further, the coil body 44 is formed such that the wire 44 a (e.g., astainless steel wire) is wound around the surface of the coil body 41 inthe same direction (clockwise, facing to the distal end) as the coilbody 43 (clockwise, facing to the distal end).

Each wire in the hollow coil body 41 and the coil body 42 is woundaround closely (see FIG. 9). The coil body 42 is twistedly formed on thesurface of the hollow coil body 41. This means that the shaft formed bythe hollow coil body 41 and the coil body 42 has a hollow shape havingan outer diameter that is smaller at a distal end than at a proximalend. The coil body 44 provides a spirally-arranged protruding portionprotruding outwardly (the outermost surface of the dilator 40, theoutermost portion) on an outer peripheral surface 41L of the hollow coilbody 41, and the coil body 43 provides a spirally-arranged protrudingportion protruding outwardly (the outermost surface of the dilator 40,the outermost portion) on an outer peripheral surface 42T of the coilbody 42. These spirally-arranged protruding portions each have gapsbetween adjacent portions (adjacent windings of the wire) along an axisA of the hollow coil body 41. Further, the coil body 43 is provided onthe coil body 42, which corresponds to a portion where the shaft has anincreasing outer diameter.

It is noted that metal wires made of stainless steel can be used for thewires of the hollow coil body 41, the coil body 42, the coil body 43,and the coil body 44, but they are not limited to stainless steel wires.They may be made of a superelastic alloy such as nickel-titanium.Further, they are not limited to metal wires and may be resin wires.

The dilator 40 (the multilayer body 47) can ensure the distal-endflexibility of the dilator 40 (the multilayer body 47) and can maintainthe pushability and torquability of the dilator 40 (the multilayer body47) even when the dilator 40 (the multilayer body 47) is longer andcurved. Further, the screw effect of the single wire 43 a and the singlewire 44 a extending contiguously toward the distal end from the proximalend of the coil body 43 can further be improved when the multilayer body47 is rotated. This enables the dilator 40 to be easily advanced notonly by a pushing operation but also by a rotational operation. Inaddition, the diameter of a pre-formed hole can be increased more easilyby the coil body 43 provided at the coil body 42 which corresponds to aportion where the shaft has an increasing outer diameter.

It is noted that when the amounts of gap between adjacent windings ofthe wire 44 a and the wire 43 a are configured so as to be graduallyreduced toward the proximal end side, the following effect can beobserved: the stiffness of the dilator 40 (the multilayer body 47) alongthe axis direction can be gradually changed so that the dilator 40 (themultilayer body 47) can easily enter into the inside of an approachpathway even when the approach pathway meanders.

Further, a shaft (the first coil) composed of the hollow coil body 41and the coil body 42 each including a plurality of wires wound aroundinto a hollow shape can improve the flexibility of the shaft and thetransmissibility of torque via the shaft. Further, a spirally-arrangedprotruding portion (the second coil) composed of the coil body 44including a single wire wound around on the outer peripheral surface 41Lof the hollow coil body 41 and the coil body 43 wound around on an outerperipheral surface 42T of the coil body 42 can be easily formed, canensure the flexibility of the distal end of the dilator 40 by virtue ofthe elasticity of the second coil, and can improve the torquability.Further, of the wires of the hollow coil body 41 and the coil body 42are wound in a direction opposite to the wires of the coil body 43 andthe coil body 44. Therefore, even when the dilator 40 is rotated in adirection to open the hollow coil body 41 and the coil body 42, a forceis applied in a direction to close the coil body 43 and the coil body 44to prevent the opening of the hollow coil body 41 and the coil body 42.This allows a force applied to the connector 9 of the dilator 40 to betransmitted to the distal end side.

FIG. 10 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments.

In FIG. 10, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 10, a dilator 50 includes: a multilayer body 57 including ahollow coil body 51 including a plurality of wires 51 a, 51 b, 51 c, 51d, 51 e, 51 f, 51 g, 51 h, 51 j, and 51 k wound around into a hollowshape; a coil body 52 proximally spaced from a distal end of the hollowcoil body 51 and including a plurality of element wires 52 a, 52 b, 52c, 52 d, 52 e, 52 f, 52 g, 52 h, 52 j, 52 k, 52 m, 52 n, 52 p, 52 q, 52r, and 52 s wound around on an outer periphery of the hollow coil body51 in the same direction (counterclockwise, facing to the distal end) asthe hollow coil body 51 (counterclockwise, facing to the distal end);and a coil body 53 including a single wire 53 a wound around on theouter peripheries of the hollow coil body 51 and the coil body 52 fromthe distal end of the hollow coil body 51 in a direction (clockwise,facing to the distal end) opposite to the hollow coil body 52. Thedilator 50 further includes a connector 9 (not shown) having a hollowshape and connected to a proximal end of the multilayer body 57.

Here, the multilayer body 57 has a stepped and cylindrical hollow shapeas in the multilayer body 27, but it differs from the multilayer body 27in that the coil body 53 in the multilayer body 57 is formed integrallyand continuously while the coil body 24, the coil body 25, and the coilbody 23 in the multilayer body 27 are formed as separate members. Thatis, in the coil body 53, the single wire 53 a is wound around closely atthe proximal end side and wound around with gaps between adjacentwindings at the distal end side of the coil body 52 and the distal endside of the coil body 51.

It is noted that the hollow coil body 51 and the coil body 52 togethercorrespond to the “shaft” and the “first coil.” The portion of the coilbody 53 wound around with gaps between adjacent windings corresponds tothe “spirally-arranged protruding portion” and the “second coil.”Further, the coil body 52 corresponds to the “portion having anincreasing outer diameter.”

The hollow coil body 51 is formed such that the wires 51 a, 51 b, 51 c,51 d, 51 e, 51 f. 51 g, 51 h, 51 j, and 51 k are 10 wires (e.g.,stainless steel wires) that are twisted into a hollow shape as in thehollow coil body 21. The hollow coil body 51 has a cylindrical hollowshape from the distal end to the connector 9.

Further, the coil body 52 is formed such that the wires 52 a, 52 b, 52c, 52 d, 52 e, 52 f, 52 g, 52 h, 52 j, 52 k, 52 m, 52 n, 52 p, 52 q, 52r, and 52 s are 16 wires (e.g., stainless steel wires) that are woundaround on a surface of the coil body 51 in the same direction(counterclockwise, facing to the distal end) as the hollow coil body 51.The coil body 52 also has a cylindrical hollow shape from the distal endto the connector 9.

Further, the coil body 53 is formed such that the wire 53 a (e.g., astainless steel wire) is wound around on the surfaces of the coil body51 and the coil body 52. The hollow coil body 53 also has a cylindricalhollow shape from the distal end to the connector 9.

Each wire in the hollow coil body 51 and the coil body 52 is woundaround closely (see FIG. 10). The coil body 52 is twistedly formed onthe surface of the hollow coil body 51. This means that the hollow coilbody 51, the coil body 52, and the closely wound portion of the coilbody 53 collectively correspond to the shaft having a hollow shape withan outer diameter that is smaller at a distal end than at a proximalend. The coil body 53 provides a spirally-arranged protruding portionprotruding outwardly (from the outermost surface and the outermostportion of the dilator 50) on an outer peripheral surface 51L of thehollow coil body 51 and an outer peripheral surface 52T of the coil body52. The above spirally-arranged protruding portion has gaps betweenadjacent portions (adjacent windings of the wire) along an axis A of thehollow coil body 51. Further, the coil body 53 is provided at the coilbody 52, which corresponds to a portion where the shaft has anincreasing outer diameter.

It is noted that metal wires made of stainless steel can be used for thewires of the hollow coil body 51, the coil body 52, and the coil body53, but they are not limited to stainless steel wires. They may be madeof a superelastic alloy such as nickel-titanium. Further, they are notlimited to metal wires and may be resin wires.

The dilator 50 (the multilayer body 57) can ensure the distal-endflexibility of the dilator 50 (the multilayer body 57) and can maintainthe pushability and torquability of the dilator 50 (the multilayer body57) even when the dilator 50 (the multilayer body 57) is longer andcurved. Further, the screw effect of the single wire 53 a extendingcontiguously toward the distal end from the proximal end of the coilbody 53 can further be improved when the multilayer body 57 is rotated.This enables the dilator 50 to be easily advanced not only by a pushingoperation but also by a rotational operation. In addition, the diameterof a pre-formed hole can be increased more easily by the coil body 53provided at the coil body 52 which corresponds to a portion where theshaft has an increasing outer diameter.

It is noted that when the amount of gap between adjacent windings of themetal wire 53 a is configured so as to be gradually reduced toward theproximal end side, the following effect can be observed: the stiffnessof the dilator 50 (the multilayer body 57) along the axis direction canbe gradually changed so that the dilator 50 (the multilayer body 57) caneasily enter into the inside of an approach pathway even when theapproach pathway meanders.

Further, a shaft (the first coil) composed of the hollow coil body 51and the coil body 52 each including a plurality of wires wound aroundinto a hollow shape can improve the flexibility of the shaft and thetransmissibility of torque via the shaft. Further, a spirally-arrangedprotruding portion (the second coil) composed of the coil body 53including a single wire wound around the outer peripheral surface 51L ofthe hollow coil body 51 and the outer peripheral surface 52T of thehollow coil body 52 can be easily formed, can ensure the flexibility ofthe distal end of the dilator 50 by virtue of the elasticity of thesecond coil, and can improve the torquability. Further, the wires of thehollow coil body 51 and the coil body 52 are wound in a directionopposite to the wire of the coil body 53. Therefore, even when thedilator 50 is rotated in a direction to open the hollow coil body 51 andthe coil body 52, a force is applied in a direction to close the coilbody 53 to prevent the opening of the hollow coil body 51 and the coilbody 52. This allows a force applied to the connector 9 of the dilator50 to be transmitted to the distal end side.

FIG. 11 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments.

In FIG. 11, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 11, a dilator 60 includes: a multilayer body 67 including ahollow coil body 61 including a plurality of wires 61 a, 61 b, 61 c, 61d, 61 e, 61 f, 61 g, 61 h, 61 j, and 61 k wound around into a hollowshape; a coil body 62 proximally spaced from a distal end of the hollowcoil body 61 and including a plurality of wires 62 a, 62 b, 62 c, 62 d,62 e, 62 f, 62 g, 62 h, 62 j, 62 k, 62 m, 62 n, 62 p, 62 q, 62 r, and 62s wound around on an outer periphery of the hollow coil body 61 in thesame direction (counterclockwise, facing to the distal end) as thehollow coil body 61 (counterclockwise, facing to the distal end); and acoil body 63 including a single wire 63 a wound around on the outerperipheries of the hollow coil body 61 and the coil body 62 from thedistal end of the hollow coil body 61 in a direction (clockwise, facingto the distal end) opposite to the hollow coil body 62. The dilator 60further includes a connector 9 (not shown) having a hollow shape andbeing connected to a proximal end of the multilayer body 67. However,the dilator 60 differs from the dilator 50 in that the multilayer body67 of the dilator 60 has a distal-end portion 66 at the distal end ofthe hollow coil body 61 while the multilayer body 57 of the dilator 50does not.

The distal-end portion 66 is formed by casting a solder material (asilver-tin solder material, a gold-tin solder material, or the like)into the distal end of the hollow coil body 61, and has a substantiallycylindrical hollow shape. Further, the surface of the distal-end portion66 is flat while the surface of the distal end of the multilayer body 57is uneven.

The multilayer body 67 has a stepped and cylindrical hollow shape as inthe multilayer body 27, but it differs from the multilayer body 27 inthat the coil body 63 in the multilayer body 67 is formed integrally andcontinuously while the coil body 24, the coil body 25, and the coil body23 in the multilayer body 27 are formed as separate members. That is, inthe coil body 63, the single wire 63 a is closely wound around at theproximal end side and is wound around with gaps between adjacentwindings at the distal end side of the coil body 62 and the distal endside of the coil body 61.

It is noted that the hollow coil body 61 and the coil body 62 togethercorrespond to the “shaft” and the “first coil.” The portion of the coilbody 63 wound around with gaps between adjacent windings corresponds tothe “spirally-arranged protruding portion” and the “second coil.”Further, the coil body 62 corresponds to the “portion having anincreasing outer diameter.”

The hollow coil body 61 is formed such that the wires 61 a, 61 b, 61 c,61 d, 61 e, 61 f, 61 g, 61 h, 61 j, and 61 k are 10 wires (e.g.,stainless steel wires) that are twisted into a hollow shape as in thehollow coil body 21. The hollow coil body 61 has a cylindrical hollowshape from the distal end to the connector 9.

Further, the coil body 62 is formed such that the wires 62 a, 62 b, 62c, 62 d, 62 e, 62 f, 62 g, 62 h, 62 j, 62 k, 62 m, 62 n, 62 p, 62 q, 62r, and 62 s are 16 wires (e.g., stainless steel wires) that are woundaround on a surface of the coil body 61 in the same direction(counterclockwise, facing to the distal end) as the hollow coil body 61.The hollow coil body 62 also has a cylindrical hollow shape from thedistal end to the connector 9.

Further, the coil body 63 is formed such that the wire 63 a (e.g., astainless steel wire) is wound around on the surfaces of the coil body61 and the coil body 62. The hollow coil body 63 also has a cylindricalhollow shape from the distal end to the connector 9.

Each wire in the hollow coil body 61 and the coil body 62 is woundaround closely (see FIG. 11). The coil body 62 is twistedly formed onthe surface of the hollow coil body 61. This means that the shaft formedfrom the hollow coil body 61 and the coil body 62 has a hollow shapehaving an outer diameter that is smaller at a distal end than at aproximal end. The coil body 63 provides a spirally-arranged protrudingportion protruding outwardly (the outermost surface of the dilator 60,the outermost portion) on an outer peripheral surface 61L of the hollowcoil body 61 and an outer peripheral surface 62T of the coil body 62.The above spirally-arranged protruding portion has gaps between adjacentportions (adjacent windings of the wire) along an axis A of the hollowcoil body 61. Further, the coil body 63 is provided at the coil body 62which corresponds to a portion where the shaft has an increasing outerdiameter.

It is noted that metal wires made of stainless steel can be used for thewires of the hollow coil body 61, the coil body 62, and the coil body63, but they are not limited to stainless steel wires. They may be madeof a superelastic alloy such as nickel-titanium. Further, they are notlimited to metal wires and may be resin wires.

According to the dilator 60 (the multilayer body 67), the distal-endportion 66 having a flat surface is connected to the distal end of themultilayer body 67. This configuration can further improve insertabilityinto a punctured portion by first pressing the dilator against thepunctured portion, and then pushing and rotating the dilator inward. Inaddition, this configuration can ensure the distal-end flexibility ofthe dilator 60 (the multilayer body 67) and can improve the pushabilityand torquability of the dilator 60 (the multilayer body 67) even whenthe dilator 60 (the multilayer body 67) is longer and curved. Further,the screw effect of the single wire 63 a extending contiguously towardthe distal end from the proximal end of the coil body 63 can further beimproved when the multilayer body 67 is rotated. This enables thedilator 60 to be easily advanced not only by a pushing operation butalso by a rotational operation. In addition, the diameter of apre-formed hole can be increased more easily by the coil body 63provided at the coil body 62 which corresponds to a portion where theshaft has an increasing outer diameter.

It is noted that when the amount of gap between adjacent windings of themetal wire 63 a is configured so as to be gradually reduced toward theproximal end side, the following effect can be observed: the stiffnessof the dilator 60 (the multilayer body 67) along the axis direction canbe gradually changed so that the dilator 60 (the multilayer body 67) caneasily enter into the inside of an approach pathway even when theapproach pathway meanders.

Further, the shaft (the first coil) composed of the hollow coil body 61and the coil body 62 each including a plurality of wires wound aroundinto a hollow shape can improve the flexibility of the shaft and thetransmissibility of torque via the shaft. Further, a spirally-arrangedprotruding portion (the second coil) composed of the coil body 63including a single wire wound around on an outer peripheral surface 61Lof the hollow coil body 61 and an outer peripheral surface 62T of thehollow coil body 62 can be easily formed, can ensure the flexibility ofthe distal end of the dilator 60 by virtue of the elasticity of thesecond coil, and can improve the torquability. Further, the wires of thehollow coil body 61 and the coil body 62 are wound in a directionopposite to the wire of the coil body 63. Therefore, even when thedilator 60 is rotated in a direction to open the hollow coil body 61 andthe coil body 62, a force is applied in a direction to close the coilbody 63 to prevent the opening of the hollow coil body 61 and the coilbody 62. This allows a force applied to the connector 9 of the dilator60 to be transmitted to the distal end side.

FIG. 12 shows a distal end portion of a dilator (a multilayer body)according to the disclosed embodiments.

In FIG. 12, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 12, a dilator 70 includes: a multilayer body 77 including ahollow coil body 21 including a plurality of wires 21 a, 21 b, 21 c, 21d, 21 e, 21 f, 21 g, 21 h, 21 j, and 21 k wound around into a hollowshape; a coil body 22 proximally spaced from a distal end of the hollowcoil body 21 and including a plurality of wires 22 a, 22 b, 22 c, 22 d,22 e, 22 f, 22 g, 22 h, 22 j, 22 k, 22 m, 22 n, 22 p, 22 q, 22 r, and 22s wound around on an outer periphery of the hollow coil body 21 in adirection (clockwise, facing to the distal end) opposite to the hollowcoil body 21; and a coil body 24 including a single wire 24 a woundaround with gaps between adjacent windings on the outer periphery of thecoil body 21 in a region distal to a distal end of the coil body 22. Thedilator 70 further includes a connector 9 (not shown) having a hollowshape and being connected to a proximal end of the multilayer body 77.

Here, the multilayer body 77 has a stepped and cylindrical hollow shapeas in the multilayer body 27 but has a two-layer structure where thecoil 25 and the coil 23 are removed from the multilayer body 27.

Even in a case where the dilator 70 (the multilayer body 77) is longerand curved, the dilator 70 (the multilayer body 77) can ensure thedistal-end flexibility of the dilator 70 (the multilayer body 77), canmaintain the pushability and torquability of the dilator 70 (themultilayer body 77), and can enable the diameter of a pre-formed hole tobe easily increased by the screw effect of the wire 24 a upon rotationof the multilayer body 77.

However, the multilayer body 77 has a two-layer structure while themultilayer body 27 has a three-layer structure. Therefore, themultilayer body 77 may have a somewhat inferior ability for increasingthe diameter of a hole as compared with the multilayer body 27.

It is noted that when the amount of gap between adjacent windings of thewire 24 a is configured so as to be gradually reduced toward theproximal end side, the following effect can be observed: the stiffnessof the dilator 70 (the multilayer body 77) along the axis direction canbe gradually changed so that the dilator 70 (the multilayer body 77) caneasily enter into the inside of an approach pathway even when theapproach pathway meanders.

FIG. 13 shows an overall view of a dilator according to the disclosedembodiments.

In FIG. 13, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 13, a dilator 80 includes a shaft 81, a spirally-arrangedprotruding portion 82, and a connector 9 connected to a proximal end ofthe shaft 81.

The shaft 81 has a hollow shape in which an inner cavity 81 a is formedextending penetratingly from the proximal end to a distal end of theshaft 81. The shaft 81 also has a body portion 83, a tapered portion 84,and a distal-end portion 85.

There is no particular limitation for the materials of the shaft 81 andthe spirally-arranged protruding portion 82 as long as they can ensurethe flexibility of the tapered portion 84 and the distal-end portion 85and have biocompatibility. For example, the following materials can beused: stainless steel; superelastic alloy materials such asnickel-titanium alloys; or synthetic resins such as polyvinyl chlorideresin, urethane resin, polyolefin resin, polyamide resin, andfluororesin.

The body portion 83 is located at the proximal end side of the dilator80, and the connector 9 is connected to a proximal end thereof. Further,the body portion 83 has a substantially constant outer diameter from theproximal end thereof through the distal end.

The tapered portion 84 is connected to the distal end of the bodyportion 83, extends from that distal end to the distal end side, and hasa shape tapered toward the distal end side. That is, the tapered portion84 is configured such that the outer diameter of the distal end sidethereof is smaller than that of the proximal end side and corresponds toa portion having an outer diameter increasing toward the proximal endside from the distal end side of the shaft 81.

The distal-end portion 85 is connected to the distal end of the taperedportion 84 and extends from that distal end to the distal end side.Further, the distal-end portion 85 has a substantially constant outerdiameter from the proximal end to the distal end thereof. As describedabove, the shaft 81 has a hollow shape having an outer diameter that issmaller at the distal end than at the proximal end.

The spirally-arranged protruding portion 82 is provided on an outerperipheral surface 81B of the shaft 81 so as to be protruding outwardly(from the outermost surface of the dilator 80, the outermost portion).The spirally-arranged protruding portion 82 is provided at a distal-endside portion of the body portion 83, at the tapered portion 84, and atthe distal-end portion 85 and has gaps between adjacent portions alongan axis A of the shaft 81. That is, the adjacent portions of thespirally-arranged protruding portion 82 are spaced from each other. Thegaps are configured so as to be gradually smaller toward the proximalend side from the distal end side of the shaft 81. The spirally-arrangedprotruding portion 82 is integrally formed with the shaft 81 by castingor the like.

In the dilator 80, the spirally-arranged protruding portion 82protruding outwardly is provided on the outer peripheral surface 81B ofthe shaft 81 and has gaps between adjacent portions along the axis A ofthe shaft 81. This configuration enables the dilator to be advanced notonly by a conventional pushing operation but also by a rotationaloperation of the spirally-arranged protruding portion 82.

Further, the spirally-arranged protruding portion 82 provided at aportion having an outer diameter increasing toward the proximal end sidefrom the distal end side of the shaft, that is, at the tapered portion84, can easily increase the diameter of a pre-formed hole.

Further, the gaps of the spirally-arranged protruding portions 82configured so as to be gradually smaller toward the proximal end sidefrom the distal end side of the shaft 81 can gradually change thestiffness of the shaft 81 along the axis direction. This can ensure theflexibility of the distal end of the shaft 81 and can maintain thepushability and torquability of the shaft 81 even when the shaft 81 islonger and curved.

FIG. 14 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments.

In FIG. 14, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 14, a dilator 90 includes a shaft 91, a spirally-arrangedprotruding portion 92, and a connector 9 (not shown) connected to aproximal end of the shaft 91. The material(s) of the shaft 91 and thespirally-arranged protruding portion 92 is/are the same as that/those ofthe shaft 81 and the spirally-arranged protruding portion 82 of thedilator 80.

The shaft 91 has a hollow shape in which an inner cavity 91 a is formedextending penetratingly from the proximal end to a distal end of theshaft 91. Further, the shaft 91 has a body portion 93 and a taperedportion 94. The dilator 90 differs from the dilator 80 in that thedilator 90 does not have a distal-end portion.

The body portion 93 and the tapered portion 94 have the sameconfigurations as the body portion 83 and the tapered portion 84 of thedilator 80. Further, the spirally-arranged protruding portion 92 isprovided on an outer peripheral surface 91B of the shaft 91 so as to beprotruding outwardly (the outermost surface of the dilator 90, theoutermost portion). The spirally-arranged protruding portion 92 isprovided at a distal-end side portion of the body portion 93 and at thetapered portion 94 and has gaps between adjacent portions along an axisA of the shaft 91. That is, the adjacent portions of thespirally-arranged protruding portion 92 are spaced from each other. Thegaps are configured so as to be gradually smaller toward the proximalend side from the distal end side of the shaft 91. The spirally-arrangedprotruding portion 92 is integrally formed with the shaft 91 by castingor the like. In the dilator 90, the spirally-arranged protruding portion92 protruding outwardly is provided on the outer peripheral surface 91Bof the shaft 91 and has gaps between adjacent portions along the axis Aof the shaft 91 as described above. The spirally-arranged protrudingportion 92 is provided at a portion having an outer diameter increasingfrom the distal end side to the proximal end side of the shaft, i.e., atthe tapered portion 94. The gaps of the spirally-arranged protrudingportions 92 are configured so as to be gradually smaller toward theproximal end side from the distal end side of the shaft 91. Therefore,the dilator 90 can produce similar effects as the dilator 80.

FIG. 15 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments.

In FIG. 15, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 15, a dilator 100 includes a shaft 101, a spirally-arrangedprotruding portion 102, and a connector 9 (not shown) connected to aproximal end of the shaft 101. The material(s) of the shaft 101 and thespirally-arranged protruding portion 102 is/are the same as that/thoseof the shaft 81 and the spirally-arranged protruding portion 82 of thedilator 80.

The shaft 101 has a hollow shape in which an inner cavity 101 a isformed extending penetratingly from a proximal end to a distal end.Further, the shaft 101 has a tapered portion 104. The dilator 100differs from the dilator 80 in that the dilator 100 does not have eithera distal-end portion or a body portion. That is, the shaft 101 has atapered shape having an outer diameter gradually decreasing from aproximal end to a distal end throughout its entire length. This meansthat the shaft 101 has a hollow shape having an outer diameter that issmaller at the distal end than at the proximal end.

The spirally-arranged protruding portion 102 is provided on an outerperipheral surface 101B of the shaft 101 so as to be protrudingoutwardly (the outermost surface of the dilator 100, the outermostportion). The spirally-arranged protruding portion 102 is provided at adistal-end side portion of the tapered portion 104 and has gaps betweenadjacent portions along an axis A of the shaft 101. That is, theadjacent portions of the spirally-arranged protruding portion 102 arespaced from each other. The gaps are configured so as to be graduallysmaller toward the proximal end side from the distal end side of theshaft 101. The spirally-arranged protruding portion 102 is integrallyformed with the shaft 101 by casting or the like.

In the dilator 100, the spirally-arranged protruding portion 102protruding outwardly is provided on the outer peripheral surface 101B ofthe shaft 101 and has gaps between adjacent portions along the axis A ofthe shaft 101 as described above. The spirally-arranged protrudingportion 102 is provided at the tapered portion 104 which corresponds toa portion having an outer diameter increasing toward the proximal endside from the distal end side of the shaft. The gaps of thespirally-arranged protruding portions 102 are configured so as to begradually smaller toward the proximal end side from the distal end sideof the shaft 101. Therefore, the dilator 100 can produce similar effectsas the dilator 80.

FIG. 16 shows a partial cross-sectional view of a distal-end sideportion of a dilator according to the disclosed embodiments.

In FIG. 16, the left side in the figure corresponds to the front endside (the distal side) which is to be inserted into the body, and theright side corresponds to the base end side (the hand side, the proximalside) which is to be operated by an operator such as a surgeon.

In FIG. 16, a dilator 110 includes a shaft 111, a spirally-arrangedprotruding portion 112, and a connector 9 (not shown) connected to aproximal end of the shaft 111. The material(s) of the shaft 111 and thespirally-arranged protruding portion 112 is/are the same as that/thoseof the shaft 81 and the spirally-arranged protruding portion 82 of thedilator 80.

The shaft 111 has a hollow shape in which an inner cavity 111 a isformed extending penetratingly from the proximal end to a distal end ofthe shaft 111. Further, the shaft 111 has a body portion 113 and adistal-end portion 115.

The body portion 113 is located at the proximal end side of the dilator110, and the connector 9 is connected to a proximal end thereof.Further, the body portion 113 has a substantially constant outerdiameter from the proximal end to the distal end thereof.

The distal-end portion 115 is connected to the distal end of the bodyportion 113 and extends from that distal end to the distal end side.Further, the distal-end portion 115 has a substantially constant outerdiameter from the proximal end to the distal end thereof. The outerdiameter of the distal-end portion 115 is smaller than that of the bodyportion 113, and the distal-end portion 115 is formed coaxially with thebody portion 113. This means that the shaft 111 has a hollow shapehaving an outer diameter that is smaller at a distal end than at aproximal end. Further, the body portion 113 corresponds to a portionhaving an outer diameter increasing from the distal end side to theproximal end side of the shaft 111.

The spirally-arranged protruding portion 112 is provided on an outerperipheral surface 111B of the shaft 111 so as to be protrudingoutwardly (the outermost surface of the dilator 110, the outermostportion). The spirally-arranged protruding portion 112 is provided at adistal-end side portion of the body portion 113 and at the distal endportion 115 and has gaps between adjacent portions along an axis A ofthe shaft 111. That is, the adjacent portions of the spirally-arrangedprotruding portion 112 are spaced from each other. The gaps areconfigured so as to be gradually smaller toward the proximal end sidefrom the distal end side of the shaft 111. The spirally-arrangedprotruding portion 112 is integrally formed with the shaft 111 bycasting or the like.

In the dilator 110, the spirally-arranged protruding portion 112protruding outwardly is provided on the outer peripheral surface 111B ofthe shaft 111 and has gaps between adjacent portions along the axis A ofthe shaft 111. This configuration enables the dilator to be advanced notonly by a conventional pushing operation but also by a rotationaloperation of the spirally-arranged protruding portion 112.

Further, the spirally-arranged protruding portion 112 is provided at aportion having an outer diameter increasing toward the proximal end sidefrom the distal end side of the shaft, that is, at the body portion 113.This configuration enables the diameter of a pre-formed hole to beeasily increased.

Further, the gaps of the spirally-arranged protruding portions 112configured so as to be gradually smaller toward the proximal end sidefrom the distal end side of the shaft 111 can gradually change thestiffness of the shaft 111 at the axis A. This can ensure theflexibility of the distal end of the shaft 111 and can maintain thepushability and torquability of the shaft 111 even when the shaft 111 islonger and curved.

Hereinbefore, the embodiments of the present disclosure are described,but the present disclosure shall not be limited to these embodiments.Rather, various modifications may be made.

For example, the hollow coil body 3, the hollow coil body 21, the hollowcoil body 31, the hollow coil body 41, the hollow coil body 51, and thehollow coil body 61 are described as hollow coil bodies including 10wires in the aforementioned embodiments, but the number of wires shallnot be limited to 10. The number may be one or more.

Further, the coil body 22, the coil body 42, the coil body 52, and thecoil body 62 are described as coil bodies including 16 wires in theaforementioned embodiments, but the number of wires shall not be limitedto 16. The number may be one or more.

Moreover, the coil body 23 and the coil body 33 are described as coilbodies including 23 wires in the aforementioned embodiments, but thenumber of wires shall not be limited to 23. The number may be one ormore.

Moreover, the distal-end portion 6 is described to be formed by castinga solder material into the distal end of the multilayer body 17.However, the outer periphery of the coil body 5 and/or the coil body 3in the vicinity of the distal-end portion of the multilayer body 17 maybe sanded to form the distal-end portion 6 having a flat surface. Thisalso applies to the distal-end portion 66.

Furthermore, the distal-end portion 6 is described as being fixed to thedistal end of the multilayer body 17. However, similar effects may beproduced by fixing a distal-end portion to the distal end of themultilayer body 27, the distal end of the multilayer body 37, the distalend of the multilayer body 47, the distal end of the multilayer body 77,the distal end of the shaft 81, the distal end of the shaft 91, thedistal end of the shaft 101, or the distal end of the shaft 111.

Further, the outer peripheries of the multilayer bodies 7, 17, 27, 37,47, 57, 67, and 77 and the shafts 81, 91, 101, and 111 and thespirally-arranged protruding portions 82, 92, 102, and 112 may be coatedwith a resin(s). For example, the outer peripheries of the shaft 81 andthe spirally-arranged protruding portion 82 of the dilator 80 may becoated with a resin 86 as shown in FIG. 17. The resin 86 can improveslidability to prevent damage to living body tissue. When the outerperiphery of the shaft 81 is coated with the resin 86, a portion wherethe body portion 83, the tapered portion 84, and the distal-end portion85 are coated with the resin 86 corresponds to the shaft 81, and aportion protruding outwardly from the outer peripheral surface 81B ofthe shaft 81 corresponds to the spirally-arranged protruding portion 82.Examples of the resin 86 include, for example, biocompatible resinmaterials such as polyamide resin and fluororesin, or hydrophiliccoating materials. The resin 86 may have a thickness of, for example,0.1 μm to 300 μm.

Further, the spirally-arranged protruding portions 82, 92, 102, and 112are configured to have gaps between adjacent portions along the axis A,the gaps becoming gradually smaller toward the proximal end side fromthe distal end side of the shaft 81. However, the gaps may be evenlyspaced. Moreover, the shafts 81, 91, 101, and 111 and the spiralprotruding portions 82, 92, 102, and 112 are integrally formed but maybe formed separately.

The shaft may have various types of coating on the side of the surfacethereof (including a portion between the shaft and the spirally-arrangedprotruding portion) other than or in addition to the resin 86 shown inFIG. 17. Examples of the coating include, for example, a protective filmon the surface of the shaft (representative example: a plating film), anunderlying film for improving adhesiveness between the shaft and thespirally-arranged protruding portion, and the like.

Preferably, the spirally-arranged protruding portions are not configuredto serve as a blade. The dilators are intended for expanding a holepre-formed on a target object (for example, the wall of a digestivetract such as the patient's stomach). Therefore, if thespirally-arranged protruding portion serves as a blade, living tissue atthe inner surface of the hole may be damaged.

For this reason, the spirally-arranged protruding portion preferablydoes not have a sharp edge at an end portion at a radially outer side ofthe shaft in a cross-section (for example, a cross-section perpendicularto the spiral direction of the spirally-arranged protruding portion 82as shown in FIG. 13). That is, the above end portion preferably has anarea having a shape including an obtuse angle or a curve (for example, acurve constituting a part of a circle or an ellipse). Thus, thespirally-arranged protruding portion is configured so as not to cutliving tissue when dilating a hole pre-formed on a target object.

What is claimed is:
 1. A dilator comprising: a hollow shaft having anouter diameter that is smaller at a distal end of the shaft than at aproximal end of the shaft; a spirally-arranged protruding portionprovided on an outer peripheral surface of the shaft, thespirally-arranged protruding portion protruding radially outward fromthe shaft; and a grip portion connected to the proximal end of theshaft, wherein the spirally-arranged protruding portion has gaps betweenadjacent portions of the spirally-arranged protruding portion along alongitudinal axis of the shaft.
 2. The dilator according to claim 1,wherein the spirally-arranged protruding portion is provided at aportion of the shaft having an increasing outer diameter toward theproximal end of the shaft.
 3. The dilator according to claim 2, whereinthe portion of the shaft having the increasing outer diameter has atapered shape having an outer diameter that is smaller at a distal endof the portion of the shaft having the increasing outer diameter than ata proximal end of the portion of the shaft having the increasing outerdiameter.
 4. The dilator according to claim 1, wherein the gaps of thespirally-arranged protruding portion are gradually smaller toward theproximal end of the shaft from the distal end of the shaft.
 5. Thedilator according to claim 1, wherein the shaft includes a coilincluding one or more wires wound around into a hollow shape.
 6. Thedilator according to claim 1, wherein the spirally-arranged protrudingportion includes a coil including one or more wires wound around on theouter peripheral surface of the shaft.
 7. The dilator according to claim6, wherein the coil is formed of a single wire that is wound around onthe outer peripheral surface of the shaft.
 8. The dilator according toclaim 6, wherein at a proximal end side of the shaft, adjacent windingsof the one or more wires are in contact with each other, and at a distalend side of the shaft, gaps are present between adjacent windings of theone or more wires, the distal end side of the shaft including a portionhaving a tapered shape.
 9. The dilator according to claim 1, wherein,the shaft includes a first coil having one or more first wires woundaround into a hollow shape, the spirally-arranged protruding portionincludes a second coil having one or more second wires wound around theouter peripheral surface of the shaft, and the one or more first wiresare wound around in a direction opposite to the one or more secondwires.
 10. The dilator according to claim 1, wherein: the shaft includesa first layer body having a plurality of first wires wound around into ahollow shape tapered toward the distal end of the shaft, and thespirally-arranged protruding portion includes a second layer body havinga single second wire wound around on a surface of the first layer bodyin a direction opposite to the plurality of first wires, and at aproximal end side of the shaft, adjacent windings of the second wire arein contact with each other, and at a distal end side of the shaft inwhich the first wires are wound around into the hollow tapered shape,gaps are present between adjacent windings of the second wire.
 11. Thedilator according to claim 10, wherein a length of the gap between theadjacent windings of the second wire in a direction of the longitudinalaxis is gradually reduced at a cylindrical portion of the shaft betweenthe proximal end side of the shaft and the distal end side of the shaft.12. The dilator according to claim 1, wherein: the shaft includes: athird layer body having a plurality of third wires wound around into ahollow shape; and a fourth layer body having a plurality of fourth wireswound around on an outer periphery of the third layer body, a distal endof the fourth layer body being spaced proximally from a distal end ofthe third layer body, and the spirally-arranged protruding portionincludes a fifth layer body having a single fifth wire wound around onthe outer periphery of the third layer body in a region distal to thedistal end of the fourth layer body, the fifth layer body having gapsbetween adjacent windings of the third wire.
 13. The dilator accordingto claim 12, further comprising: a sixth layer body including aplurality of sixth wires wound around on an outer periphery of thefourth layer body, a distal end of the sixth layer body being spacedproximally from the distal end of the fourth layer body, and a seventhlayer body including a single seventh wire wound around on the outerperiphery of the fourth layer body in a region distal to the distal endof the sixth layer body, the seventh wire being wound in the samedirection as the fifth wire, and the seventh layer body having gapsbetween adjacent windings of the seventh wire.
 14. The dilator accordingto claim 12, wherein the fifth layer body is integrally formed with thefourth layer body.
 15. The dilator according to claim 13, wherein theseventh layer body is integrally formed with the sixth layer body. 16.The dilator according to claim 13, wherein the sixth layer body isintegrally formed with the seventh layer body.
 17. The dilator accordingto claim 16, wherein a length of the gap between adjacent windings ofthe sixth wire in the sixth layer body, and a length of the gap betweenadjacent windings of the seventh wire in the seventh layer body aregradually reduced toward the proximal end of the shaft.
 18. The dilatoraccording to claim 1, comprising a distal end having a smooth outersurface.